Catalytic Converters do not fail on their own. The most typical scenario is that an over-rich fuel mixture--caused by a defective fuel injection or carburetor setup--allows un-burnt fuel to find its way into the converter. Therefore, due to the heat generated in the catalysation process, the fuel burns inside the converter. The substrate in the converter melts, then breaks up, resulting in exhaust system clogging and rattles.
Installing a new converter on a vehicle with fuel system problems will result in failure of the new converter. This can happen in as little as 100 miles.
Substrate meltdown is not covered by the manufacturer’s warranty. Before installing a replacement converter, be certain that fuel and ignition systems are functioning properly, that valve clearances are correct, and that all other emission equipment is in place and operating correctly. http://www.international-auto.com/index.cfm?fa=ad&aid=92
Also see: How Does A Catalytic Converter Wear Out
The outside metal temperatures of some types of converters may approach
800 to 1000 F under conditions of extremely high engine loading. ...
catalytic converter surface temperatures do not represent a new type of problem for automobile manufacturers and users as long as the engine is running properly. ...
However, if there is a partial ignition system failure, such as one or more misfiring spark plug or defective ignition wires, the temperatures of the catalytic converter surfaces and the exhaust system downstream from the converter may reach 1200 to 1400 F. This is because of the abnormal amount of unburned fuel delivered by the nonfiring cylinders. Further, once hot, the converter will take longer to cool off than other parts of the exhaust system because of its greater mass. This points out the need for careful attention to vehicle maintenance and alertness by vehicle owners to any signs of abnormal engine operation. http://www.tceq.state.tx.us/implementation/air/mobilesource/vetech/catfire.html
Back to Converters
